🚀 Java Feature Evolution from Java 8 to Java 11 to Java 17 to Java 21 to Java 25 – Full Code Examples & Real Benefits
We’ll explore the most impactful developer-facing features from Java 8 to Java 11 to Java 17 to Java 21 to Java 25.
For each feature, you’ll see:
- ✅ Modern Java code
- 🕰️ What the code looked like before the feature existed
- 🌿 The benefit explained in simple terms
🪄 Java 8 – The Start of Modern Java
1. Lambda Expressions
// ✅ Java 8 and later
List<Integer> nums = Arrays.asList(1, 2, 3);
nums.forEach(n -> System.out.println(n));
🕰️ Before (Java 7):
List<Integer> nums = Arrays.asList(1, 2, 3);
for (Integer n : nums) {
System.out.println(n);
}
🌿 Benefit: Lambdas remove unnecessary code. Instead of writing full loops, you express what to do, not how to do it.
2. Stream API
// ✅ Java 8+
List<Integer> nums = Arrays.asList(1, 2, 3, 4);
List<Integer> result = nums.stream()
.filter(n -> n > 1)
.map(n -> n * 2)
.collect(Collectors.toList());
🕰️ Before (Java 7):
List<Integer> nums = Arrays.asList(1, 2, 3, 4);
List<Integer> result = new ArrayList<>();
for (Integer n : nums) {
if (n > 1) {
result.add(n * 2);
}
}
🌿 Benefit: Streams make your intent crystal clear, avoid mutating lists manually, and reduce boilerplate for filtering, mapping, and collecting.
3. Optional
// ✅ Java 8+
Optional<String> name = Optional.ofNullable(getName());
System.out.println(name.orElse("Unknown"));
🕰️ Before (Java 7):
String n = getName();
if (n == null) {
n = "Unknown";
}
System.out.println(n);
🌿 Benefit: Optional helps avoid NullPointerException and clearly signals that a value might be missing.
4. Default Methods in Interfaces
// ✅ Java 8+
interface Greeter {
default void greet() {
System.out.println("Hello!");
}
}
🕰️ Before (Java 7):
abstract class AbstractGreeter {
void greet() {
System.out.println("Hello!");
}
}
class MyGreeter extends AbstractGreeter {}
🌿 Benefit: No need to use abstract classes for shared behavior in interfaces. Easier evolution of APIs without breaking old code.
5. Date-Time API
// ✅ Java 8+
LocalDate today = LocalDate.now();
System.out.println(today);
🕰️ Before (Java 7):
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(sdf.format(date));
🌿 Benefit: New API is immutable, thread-safe, and much easier to format/parse than java.util.Date.
🧭 Java 11 – Small but Mighty Improvements
1. var in Lambda Parameters
// ✅ Java 11
list.forEach((var s) -> System.out.println(s.toUpperCase()));
🕰️ Before (Java 8):
list.forEach((String s) -> System.out.println(s.toUpperCase()));
🌿 Benefit: Less clutter – cleaner lambdas, especially when adding annotations to parameters.
2. HTTP Client API
// ✅ Java 11
HttpClient client = HttpClient.newHttpClient();
HttpRequest req = HttpRequest.newBuilder(URI.create("https://example.com")).build();
HttpResponse<String> res = client.send(req, HttpResponse.BodyHandlers.ofString());
System.out.println(res.body());
🕰️ Before (Java 8):
URL url = new URL("https://example.com");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
try (BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()))) {
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
}
🌿 Benefit: A modern, simpler HTTP API without clunky HttpURLConnection and manual stream handling.
3. Launch Single-File Source Programs
# ✅ Java 11
java Hello.java
🕰️ Before (Java 8):
javac Hello.java
java Hello
🌿 Benefit: Easier for quick scripts, demos, and testing without a build step.
🦾 Java 17 – Pattern Matching, Records & Sealed Classes
1. Pattern Matching for instanceof
// ✅ Java 17
if (obj instanceof String s) {
System.out.println(s.toUpperCase());
}
🕰️ Before (Java 8):
if (obj instanceof String) {
String s = (String) obj;
System.out.println(s.toUpperCase());
}
🌿 Benefit: No redundant casting. Code is cleaner and safer.
2. Records
// ✅ Java 17
record Point(int x, int y) {}
Point p = new Point(1, 2);
System.out.println(p.x());
🕰️ Before (Java 8):
class Point {
private final int x;
private final int y;
Point(int x, int y) {
this.x = x;
this.y = y;
}
public int getX() { return x; }
public int getY() { return y; }
@Override
public boolean equals(Object o) { ... }
@Override
public int hashCode() { ... }
}
🌿 Benefit: Records cut tons of boilerplate for immutable data carriers.
3. Sealed Classes
// ✅ Java 17
sealed interface Shape permits Circle, Square {}
final class Circle implements Shape {}
final class Square implements Shape {}
🕰️ Before (Java 8):
interface Shape {}
class Circle implements Shape {}
class Square implements Shape {}
// Anyone could extend Shape accidentally
🌿 Benefit: Control inheritance and maintain strict type hierarchies.
🧵 Java 21 – Virtual Threads, Patterns, String Templates
1. Virtual Threads
// ✅ Java 21
Thread.startVirtualThread(() -> System.out.println("Virtual thread"));
🕰️ Before (Java 8):
new Thread(() -> System.out.println("Platform thread")).start();
🌿 Benefit: Virtual threads are lightweight – handle thousands of concurrent tasks without expensive OS threads.
2. Record Patterns
record Point(int x, int y) {}
Object o = new Point(3, 4);
if (o instanceof Point(int x, int y)) {
System.out.println(x + ", " + y);
}
🕰️ Before (Java 8):
if (o instanceof Point) {
Point p = (Point) o;
System.out.println(p.getX() + ", " + p.getY());
}
🌿 Benefit: Less casting, cleaner destructuring.
3. String Templates (Preview)
String name = "Alice";
String msg = STR."Hello, \{name}";
System.out.println(msg);
🕰️ Before (Java 8):
String msg = "Hello, " + name;
System.out.println(msg);
🌿 Benefit: More readable and secure string formatting.
4. Sequenced Collections
List<String> list = List.of("a", "b", "c");
System.out.println(list.getFirst());
System.out.println(list.getLast());
🕰️ Before (Java 8):
System.out.println(list.get(0));
System.out.println(list.get(list.size() - 1));
🌿 Benefit: Direct methods for first/last elements – cleaner, less error-prone.
🧪 Java 25 (Preview) – Even Less Boilerplate
1. Implicitly Declared Classes & Instance Main
// ✅ Java 25
void main() {
System.out.println("Hello Java 25");
}
🕰️ Before:
public class Main {
public static void main(String[] args) {
System.out.println("Hello old Java");
}
}
🌿 Benefit: Less ceremony for simple programs and scripts.
2. Primitive Type Patterns in switch
Object o = 42;
switch (o) {
case int i -> System.out.println("Int: " + i);
case String s -> System.out.println("String: " + s);
default -> System.out.println("Other");
}
🕰️ Before:
if (o instanceof Integer) {
int i = (Integer) o;
System.out.println("Int: " + i);
} else if (o instanceof String) {
System.out.println("String: " + o);
} else {
System.out.println("Other");
}
🌿 Benefit: switch becomes more powerful and expressive – less if-else nesting.
3. Stream Gatherers
List<Integer> nums = List.of(1, 2, 3, 4, 5);
nums.stream()
.gather(Gatherers.windowFixed(2))
.forEach(System.out::println);
🕰️ Before:
List<List<Integer>> windows = new ArrayList<>();
for (int i = 0; i < nums.size(); i += 2) {
windows.add(nums.subList(i, Math.min(i + 2, nums.size())));
}
windows.forEach(System.out::println);
🌿 Benefit: Easier to do advanced stream operations without custom collectors or manual loops.
🏁 Conclusion: Why This Matters
- ✅ Modern Java is cleaner, safer, and more expressive.
- 🧹 Less boilerplate → faster development.
- 🧠 Features like records, patterns, and virtual threads make your intent clear.
- 📈 Upgrading your Java version isn’t just about performance or security – it’s about developer productivity.
👉 If you’re still stuck on Java 8 or 11, now’s the perfect time to start modernizing your codebase gradually.
Hi there, just wanted to tell you, I loved this post. It was funny. Keep on posting!
Ahaa, its fastidious discussion about this article here at this website, I have read all that, so now me also commenting here.
Wow, this article is pleasant, my sister is analyzing these things, thus I am going to let know her.
You made some nice points there. I did a search on the topic and found most persons will consent with your website.
I am sure this paragraph has touched all the internet users, its really really good article on building up new weblog.
Way cool! Some extremely valid points! I appreciate you penning this article and the rest of the website is very good.
[…] 1- Learn Java 8 to Java 25 (LTS Versions Only) – Why You Must Migrate Now→ Covers lambdas, streams, records, virtual threads, sealed classes, and modern Java best practices. […]
Hello, i feel that i noticed you visited my blog thus i came to return the desire?.I’m attempting to to find issues to improve my site!I suppose its ok to make use of a few of your ideas!!
**mitolyn reviews**
Mitolyn is a carefully developed, plant-based formula created to help support metabolic efficiency and encourage healthy, lasting weight management.
I wanted to thank you for this very good read!! I absolutely loved every bit of it. I’ve got you book-marked to check out new things you
It’s very effortless to find out any matter on web as compared to textbooks, as I found this piece of writing at this site.
Hi there, I log on to your blog daily. Your humoristic style is witty, keep up the good work!
Why viewers still use to read news papers when in this technological world everything is presented on web?
What’s up, its pleasant article regarding media print, we all know media is a great source of facts.
Helpful info. Lucky me I found your web site by accident, and I am surprised why this twist of fate did not took place in advance! I bookmarked it.
Thanks for another great article. Where else could anybody get that kind of information in such a perfect way of writing? I’ve a presentation next week, and I am on the look for such information.
Nice overview of Java’s evolution from 8 to 25, with practical code examples and real benefits. This post is really helpful for planning migrations and staying up to date.
Your ability to connect with your readers is amazing.